Reactions of triaryl derivatives of Group 5 with selenium dioxide

Abstract

Triarylphosphines PR₃(R = Ph, C₆H₄Me-o, -m, -p, or C₆H₄Cl-p) react with selenium dioxide suspended in benzene or in solution in ethanol to give triarylphosphine oxides, PR₃O, and triarylphosphine selenides, PR₃Se, or selenium, depending on the phosphine, the relative proporfions of the reagents, and the solvent. Triarylarsines do not react with SeO₂ in ethanol, but reactions in benzene suspension give triarylarsine oxides or the addition compounds 2AsR₃O·H₂SeO₃ and selenium. Triphenylstibine reacts with SeO₂, suspended in benzene or in ethanol solution to give the addition compound SbPh₃O·SeO₂ and selenium. Triarylbismuthines react with SeO₂, in benzene–ethanol to give areneseleninic acids and bismuth(III)selenite. Possible mechanisms are discussed.